Bruce Bartlett is a recording engineer, microphone engineer, and technical writer. He has written 400 articles and five books on audio topics, such as "Recording Demo Tapes at Home" and "Practical Recording Techniques" published by Howard Sams. Another of his titles is "Stereo Microphone Techniques" published by Focal Press. Bruce is a member of the Audio Engineering Society.
Before the mid-sixties, all recordings were mixed live to stereo or mono. Many of them sounded fantastic. These days we record everything on multitrack, but we ought to rediscover the art of 2-track recording. Why? The sound can be much more transparent and punchy.
If you mix directly to 2-track DAT, the signal goes through your mixer only once -- during recording -- not twice during recording and mixdown. There's only one tape generation. The signal path is as short as possible, so the sound is extra clean and clear. What's more, you save recording time because you omit the overdubs and mixdown.
Recording live to 2-track is exhilarating. The band you record has to perform well all the way through the song, so they must be well rehearsed. And you have to do a flawless mix as the band plays. All the musicians must play or sing at the same time; you can't overdub. But this can be a blessing in disguise. Musicians often play better when they can interact and feed off each other's energy.
With multi-miking, you mike each instrument and singer, and mix them live to 2-track. This method works best with rock, pop, folk or jazz.
With stereo miking, you record a musical ensemble with a stereo mic or a matched pair of mics. You pick up the group as a whole, along with the room acoustics. This method works best for an orchestra, symphonic band, choir, pipe organ, string quartet, or soloist. Sometimes it works well for a folk group or acoustic jazz group. Stereo miking sounds relatively muddy when used to record a rock band, but it can be done.
Also consider using an outboard A/D converter for better sound. Connect your mic preamp outs to the converter ins. Then connect the converter outputs to your DAT's digital inputs.
You could even connect a compressor/limiter between the mic preamp and DAT analog line in. The compessor will prevent excessive peaks from overloading your DAT. This is a useful feature when you record live concerts, where you can't predict the recording level. Most portable DATs have a limiter built in.
If you're multi-miking, plug your mixer's bus 1 and 2 outputs into your recorder's line inputs. If you're grouping inputs on your mixer, plug the stereo bus out to recorder line in. The sound will be cleaner if you don't set up groups, so try to mix everything directly to busses 1 and 2.
When recording a concert, don't record the mix off the PA mixing console -- it will sound bad. The PA mix is meant to augment the live sound of the band and monitors, not to sound good by itself. Instead, connect the direct outs from the PA mixer's mic channels to the line inputs of a separate recording mixer (Fig. 1). Or split the mics to feed the PA mixer and your recording mixer (Fig. 2).
Mike each instrument and singer. You can reduce leakage by miking close and recording direct. Have vocalists sing with lips touching the foam pop filters on their microphones. Use direct boxes or guitar simulators instead of mics. Direct boxes give a clean, tight sound since they pick up no background noise or leakage. In the studio, don't use a bass amp; record the bass guitar direct and monitor it with headphones instead. This keeps the muddy-sounding bass notes from bouncing around the room.
What if you don't have enough mics? Sometimes you can pick up two instruments with one mic. Try miking the drum set with one mini omni condenser mic, about 4 " above the snare rim in the middle of the set. Boost the bass and treble a little. Another mic goes in the kick.
Now set the master faders to design center (0 dB, about 3/4 up). While listening to the mixer output, bring up the bass-player's fader and ask him or her to play the loudest part of the song. On the mixer, set the bass fader to design center. Adjust the gain-trim pot to get a 0 VU level on the mixer's meters.
Listen carefully to check for hum, noise, and buzzes. Repeat these steps for each instrument and vocal. The lead vocal might need a compressor; patch it into the vocal channel's access jacks.
Next, have the musicians play the tune while you set up a mix. You might start by raising all the faders to about -10 dB. Pan each mic as desired. Then adjust the faders so you can hear everyone about equally. Make sure you can hear each instrument in the mix.
With the balances roughed in, tweak up EQ. Close-miked vocals will need some bass rolloff to sound natural, about -6 dB at 100 Hz. You might have to turn up the monitors or headphones to hear the mix better. When the band stops, do a quiet playback so you can check your EQ settings at home-stereo levels.
Keep the mixer level peaking around 0 maximum. Set your DAT recorder's input level so its meters peak at -3 maximum. That setting allows a little headroom in case the band plays louder. Finally, add effects.
Once you're happy with the mix, record about a minute of the tune. Then play it back. Make any adjustments needed and re-record. You'll have to whip the band into shape because you can't fix mistakes by punching in. But you can always do another take. Or do several takes, and edit together the best parts of all the takes.
Set up two identical mics on a stereo bar, or use a stereo mic or dummy head. One stereo mic technique that works well in most situations is called ORTF. Take two cardioid mics, angle them apart 110 degrees (+/- 65 degrees off center), and space their grilles 7 inches apart horizontally.
Place the mic stand about 12 feet in front of the front-row musicians and raise it about 14 feet high (Fig. 3). The mics should aim down toward the ensemble. Run a long pair of mic cables to your recorder.
As the group rehearses, monitor the input signal. If the sound is too edgy, dry, or detailed, move the mics a foot or two farther away and listen again. If the sound, however, is too distant and muddy, move in a foot or two. Try to find a spot where you hear a pleasing blend of the group and the hall acoustics.
If you use good mics, you'll be amazed at the realism and purity of sound you can get with this method.
What if the sound is distorted, even though you did not reach 0 on your meters? Chances are, the mics put out a signal strong enough to overload your DAT mic preamp. To prevent this, switch on the pad (attenuator) on your DAT or mic preamp. If you find that you're setting the record-level knob less than halfway up to prevent excessive meter peaks, you probably need to use the pad. Always turn on the pad when you record a rock concert.
Another source of distortion is the microphones. Most mics can handle at least 120 dB SPL without distorting. But if the concert is louder than that, a mic rated at 120 dB SPL maximum will break up. You may need a mic that can handle 130 dB SPL or more. Check the mic's spec sheet under "Maximum SPL." Some condenser mics have a built-in pad that lets them handle high SPLs without distortion. Well-designed dynamic mics do not distort, even with very loud sounds.
If a taper's section is set up in the audience, as in the Grateful Dead concerts, it's legal to record the concert. Otherwise, it's not -- unless you have the artists' permission.
You'll need a portable DAT and a stereo mic or a matched pair of mics. Some people use a binaural set of mics that fit on the head (such as made by CORE). Or you can clip mini omni mics to your shoulders. Small electret mic capsules can be powered with a battery, and can plug directly into your DAT mic inputs.
If you can, sit fairly close to the band so the mics will pick up less room reverb. But don't sit too close, or you'll be far off-axis to the PA speakers, where the treble is weak.
Some people get a good result by putting a stereo mic at the PA mixing console. They mix that mic with a direct feed from the console.
Do a trial recording and play it back. Is anyone too quiet? Have them move a little closer to the mics and try again. Do you want to hear more room acoustics? Move the mics a foot or two farther from the group and re-record. Check the playback and decide if the sound is okay.
If you're recording a concert, try to mic close to get the clearest sound. Close miking lets you pick up more of the group and less of the PA speakers. Ask whether you can put your mics on stage; some musicians prefer that you don't. Often the best you can do is sit in the front row, and put your mic stand in front of you.
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